Stretch-forming machine



March 27, 1956 R. GRAY ET AL 2,739,634

STRETCH-FORMING MACHINE Original Filed Sept. 2, 1950 2 Sheets-Sheet l Gttorneg March 1956 R. GRAY ET AL 2,739,634

STRETCH-FORMING MACHINE Original Filed Sept. 2, 1950 2 Sheets-Sheet 2 3nnentors LAA/DO/V R GRAY HARRY f? 5M/ TH, JR.

Gttorneg ilnited States. Patent O 2,739,634 STRETCH-FDRMING MACHINE Landon B. Gray, Manhattan Beach, and Harry P. Smith, Sir Los Angeles, Calif., assignors to Richard Seifried, Playa Del Rey, Calif.

Griginal application September 2, 1950, Serial No. 182,928, new Patent No. 2,632,493, ,dated March 24,

1953. Divided and this application January 5, 1952,

Serial No. 265,122

2 Claims. (Cl. 153 -32) Another object of the invention is to provide a s'tr'etchforming machine having swingable arms that adjustably carry tension-imparting units on the arms, and provided with a single hydraulic arm-actuating unit on a rearward extension of the base that mounts the arms, whereby controlled power may be applied to swing said arms in unison during a stretch-forming operation.

The invention also has for its objects to provide such means that are positive in operation, convenient-in use, easily installed in a working position and easily disconnected therefrom, economical of manufacture, relatively simple, and of general superiority and serviceability.

The invention also comprises novel details of construction and novel combinations and arrangements of parts, which will more fully appear in the course of the following description. However, the drawings merely show and the following description merely describes one embodiment of the present invention, which is given by way of illustration or example only.

In the drawings, like reference characters designate similar parts in the several views:

Fig. 1 is a plan view, with one arm of the machine partly broken away, of a preferred embodiment of the invention.

Fig. 2 is a front elevational view thereof.

Fig. 3 is an enlarged and partial cross-sectional view as taken on line 3-3 of Fig. 2.

Fig. 4 is a cross-sectional view as taken on line 4-4 of Fig. 3.

Fig. 5 is a horizontal sectional'view, to the scale of Figs. 1 and 2, the same being taken on line 5-5 of Fig. 2.

The machine that is illustrated comprises, generally, a base ill, a pair of bending arms 11 carried by said base on pivots 12, an arm-actuating assembly 13 carried by the base, a cross-head 14 movable along the base by assembly 13, actuating links 15 connecting arms 11 and cross-head 14, a tension cylinder assembly 16 carried by each arm, and means 17 for effecting traverse of said assemblies to a desired location along each respective arm.

The base comprises a fabricated structure having a forward frame part 18 that is provided with a table top 19 in which are formed a plurality of key-receiving grooves 2i) that extend transversely. The top 19 is wider than frame part 18 and, as best seen in Figs. 4 and S, is provided with laterally extending bearing brackets 21 at a pivot 37 to cross-head 14.

2 for pivot pins 22. The base 10 is provided with an elongated rearwardly extending frame part 23 and the opposite side faces 24 of frame parts 18 and 23 are preferably parallel with bearing brackets 21 extending laterallyfrom said faces as seen in Figs. 4 and 5.

Frame part 18 is provided with a front wall 25 that encloses brackets 21 fromthe'front, said wall also forming part of the support for said brackets. Table top 19servesas a support fora die 26 around which a piece of stock'27 is bent, said die being adjustably positioned on the table top'and locked in position by a key 28 in a selected groove 20.

As will be seen from Fig; 3, frame part 23 is substantially lower than part 18, the top of the former being provided with a slideway 29 along which cross-head 14 moves. 1 i

1 Thearms 11 are alike'and each is provided at one end with hearing ears Bio-through which the respective pivot pins 22 extend. In this manner, the arms are mounted to swing on their pivots between an aligned position transversely of the base 10 and a position parallel to each other and to the base sides 24.

Each arm' l l' is provided with a top plate 31 that has aiset of transverse key r'eceiving grooves 32 in the upper face thereof. Each arm because of the large size thereof,

is preferably fabricated of sheet stock, as best seen in Fig. 5, and the same is formed with a longitudinal elongated opening 33extending through the arm and with a tapered groove 34 in the rear face of the arm and forming an extension oflopening 33. On the forward face of each arm is provided forwardly extending brackets 35, the same embodying a pivot 36. One end of each link 15 is connected to each respective pivot- 36 and each linkextends from the forward side of each arm throughopening 33 therein, and is pivotally connected, It will be clear, therefore, that opening 33 and tapered groove 34 of each arm cooperate to provide clearance for link 14 during all positions of the arms on their pivots. The dot-dash line position of arm11 and link 14 shows such clearance when the-arm is moved to parallelism with base sides 24. It will be noted that pivots 12, 36 and 37 never achieve a straight-line position although such a position is gradually approached when arm 11 is swung to said dot-dash line position, therefore, movement of the cross-head 14' will result in swinging movement of the arm as desired. 3

Arm-actuator assembly 13 can be controlled to move cross-head 14 in a manner to swing arms 11 as desired and depending on the resistance to bending of workpiece 27. Said assembly extends from base wall 25 rearward toward but short of slideway 29. Said assembly'comprises a cylinder 38 in which operates a piston 39, the latter having a stem 40 that extends rearwardly through the end 41 of the cylinder and connects, by means of a pin 42, to cross-head 14. Fluid-pressure conducting pipes43 and 44 are connected to opposite ends of cylinder 38, it being evident that admission of pressure through one pipe will cause movement of the cross-head in one direction, and admission of pressure through the other pipe will cause reverse movement of the cross-head.

The cross-head 14, as explained, is mounted to slide along slideway 29 under control of assembly 13 and it will be clear that such movement causes simultaneous swinging movement of both arms 11, either rearward or forward as desired. It will be seen from the present arrangement that uniform movement of the cross-head results in the arms 11 first swinging quite rapidly and then more slowly as the more straightened position of the pivots 12, 36 and 37 is approached. Thus, although the cross-head may be uniformly moved, the swing of arms .Patented Mar. 27, 1956' ing vertical trunnions 48 engaged; with the, bracket; 45,

to mount said cylinder to swing in a horizontal plane, a piston in said cylinder and having a stem 49, that egrtends outwardly of the cylinder in a, direction toward the front of die 26 .on table top 19 and a jaw, or choc-lg 50 on the projecting end of said stem. It will be clear that pressure fluid is adapted to project or retract chuck. 50, the retracting movement of both chucks effecting stretch of a work-piece 27 clamped by its ends in said chuck.

The above-described tension cylinder assemblies 15 are carried bodily by the respective swinging arms 11 and are also swingable on trunnions 48, to assume an angular position relative to said arms during theproeess of stretching and bending a work-piece around die 26;.

Both jaws 56 may be simultaneously retracted, or only one may be retracted, or one retractedat a greater rate than the other, as desired.

Since the vertically-spaced pivot pinsf22- connect the vertically-spaced bearing cars 30 of arms 11, the long pivotal bearings thus provided strongly resist any turn? ing moment relative to the axes of said pivotal'beara ings that is set up by reason of the bending forces on;

work-piece 27 being above said bearings. Itwill be noted that trunnions 48 are rearwardly offset with respect to pivots 22 and the general longitudinal line of arms 11 Therefore, tension cylinders 16 are always on the die side of the arms mounting them, and such rearward offset of units 163'. further minimizes any tendency of the armsIQ torsion ally deflect under stretch forces setup in the machine.

when the latter are aligned as in Fig. l.

The means 17 is provided toobviate manual handling of assemblies 16 which, in larger machines, may be.

quite heavy. As shown, means 17 on each arm. 11 coma prises a lead screw 51 releasahly connected at 52to bracket 45 and driven by an electric, motor 53. through a; suitable reduction gear unit 54. When key 46 isremqvcdy the means 17 can be operated to move assembly 16 along arm 11 to a position desired. Thekey is then replaced to lock the position of said assembly.

While the invention that has been illustrated and deia scribed is now regarded as the preferred embodiment, the construction is, of course, subject to modifications without departing from the spirit and scope of the invention. It is therefore not desired to restrictthe invention to the particular form of construction illustrated and described, but to cover all modifications that may fall within the scope of the appended claims.

Having thus described the invent on, what is claimed,

and desired to be secured. by Letters Patent is:.

1. In a machine of the character described, an elon-.

gated, generally straight-sided fixed base, two vertically aligned of spaced ears fixedly extending laterally from each sideof said base immediately adjacent the forward end thereof, axially aligned pivot pins extending between each pair of ears on each side of the base, an arm provided with vertically spaced ears connected with the pivot pins on each side, of the base, each arm, thereby, being pivotally connected to vertically spaced upper and lower front portions of the base to hold said arms, in all pivotal positions thereof, against forces exerting a turning mtn'nent relative to. the axes of the pivot pins on each side, a die supported on the base above and rearward the pivots, a support mounted on each arm, an articlegripping and -t ensioning unit pivotally mounted on said support and above the same in general horizontal alignment with the mentioned die, and means carried by the base and connected to the arms to swing the latter between an aligned: position transverse to the base and a position alongside of and parallel to the base to bend an artielecxtending between said units around the die into. a substantially U.-shape, the forces exerted to bend I said article being applied above the arms and pivots, creating the mentioned bending moment resisted by the vertically-spaced pivot pins, the vertical pivot mounting of each said unit on its respective arm being offset rearwardly relative-to; the. arms and the pivot pins thereof when; said; armsare in the mentioned aligned position, the line of pull on each unit, thereby, being oifset relative to he. arm carrying-the same and in a direction toward he-d e.

2. In a machine according to claim 1: the means can fifilihy thebase and'ccnnected to the arms including a cross-head movable along the base and a link connecting aid. creas-hea and each respective arm, each link having apivo el connection with its respective arm and said connections beingat the forward sides of the arms and forwardly of the'arm pivots, when the arms are in the mentioned aligned position, whereby the mentioned oifset; pivotmouutingiof the units are disposed on a line between; the-cross-head: and the line on which the pivotal connections-of the-links and arms are disposed when the arms are valigned. v t

R fe ences C tedinthefile of i Patent STATES PATENTS OTHER REFERENCES Developmentinstretch Presses, by C. L. Fenn, page .0 r licdunqn;otameric Ma hi Magazine, ust

ater Capacity B sses Pos ibil e for re y J. J. Sloan, Automotive Industries magazine, Dec. 15,

1948. pa e 36. relied upon. 

